Among 3D printing technologies, the photo-curing rapid molding technology is relatively common. In the technology, photosensitive resin (UV) in a liquid state performs polymerization under the irradiation of light. A light source irradiates according to a cross-section shape of an entity to be cured so that the liquid photosensitive resin cures, molds, accumulates, and overlaps and a cured entity is formed finally.
Currently, a photo-curing rapid molding device based on the above-mentioned principle mainly comprises a selective laser curing device (SLA, which is also referred to as a stereoscopic photo-curing molding device) and a mask photo-curing device (DLP).
The selective laser curing device uses laser with a specific intensity and a 405 nm wavelength to focus onto the surface of the liquid photosensitive resin so as to make the surface cure sequentially from point to line and from line to surface, thus completing a cross-section thin layer of an object to be printed. Subsequently, another cross-section thin layer is cured in this manner. The first and second cured cross-section thin layers are overlapped and in this manner a three-dimensional object to be printed is completed finally. Due to the usage of the above-mentioned curing procedure, when printing a large three-dimensional object or printing a plurality of three-dimensional objects, the speed of this 3D printing device based on SLA technology is slow and the efficiency is low.
The mask photo-curing device uses a DLP projector to project a two-dimensional graph of a certain cross section of the object to be printed on the liquid photosensitive resin so as to make the liquid photosensitive resin to cure a thin layer with a corresponding shape according to this graph. Then, the cured thin layers are adhered and accumulated layer by layer so as to form a cured printed object. The mask photo-curing device can print a relatively large three-dimensional object rapidly and has a relatively high resolution. However, since a DLP device has to be used, the price is high, which cannot be afforded by common customers.
In addition, whether for the selective laser curing device or for the mask photo-curing device, they both have complex light paths, which introduces relatively long delay during printing and thus reduces the curing efficiency.
Another photo-curing printer uses an LCD display unit to display a cross-section pattern of the object to be printed. A light source with 300 nm˜700 nm wavelength irradiates the LCD display unit, and after light rays transmit the LCD display unit, the liquid photosensitive resin in the resin pool is cured to a corresponding shape. However, the service life of this type of printer is very short.